Dehydrogenation Reactions during Atomic Layer Deposition of Ru Using O₂

The surface reactions during the atomic layer deposition (ALD) of Ru using an organometallic precursor [CpRu(CO) 2 Et] and O 2 gas were studied using quadrupole mass spectrometry. The analysis of the gas phase species showed that the surface chemisorption of CpRu(CO) 2 Et resulted in the formation of combustion products such as CO 2, CO, and H 2 O. Additionally, H 2 was detected as a major surface reaction product during the metal pulse. Strikingly, during the O 2 pulse virtually no H 2 O or other H-containing reaction products were measured. The key conclusion of these observations is that dehydrogenation reactions occur on the Ru surface, resulting in the release of a large fraction of the precursor’s hydrogen, predominantly in the form of H 2 . On the basis of the catalysis literature, we infer that dehydrogenation reactions can also occur during other noble metal ALD processes.